Spatial variation of seed rain and seed banks in gaps of karst forest in the Maolan Nature Reserve, Guizhou Province

Abstract

Based on an investigation on gaps and non-gap stands of the Maolan National Karst Forest Nature Reserve, Guizhou Province, quantitative characteristics and dynamic changes of seed rain and seed banks in gaps were analyzed. The results show that the total amount of seed rain was 117.4 ± 32.6 seeds/m2 during the period of observation. The number of immature seeds was 56.3 ± 10.3 seeds/m2, that of mature damaged seeds was 15.7 ± 4.7 seeds/m2, and the number of mature germinated seeds was 45.4 ± 8.2 seeds/m2. It is suggested that the seed number is rich for gap regeneration. Seed rain in gaps has spatial and temporal heterogeneities which deeply affect regeneration patterns of gap plants. Along a gradient from the gap center to a non-gap stand, seed density in the litter layer, the number of species, and the Shannon-Wiener diversity index were gradually reduced, but these indices increased in the soil. The seed density in the gap center was 2415 ± 639 seeds/m2, near the gap center was 2218 ± 421 seeds/m2 and at the gap border area 1815 ± 311 seeds/m2. This shows that plants in gaps have good latent regeneration potential. In both gaps and non-gap stands, the Jaccard similarity index of seed in litter layer was the largest, second largest at 5–10 cm soil depth, and the least at the 0–5 cm soil layer the index. The Jaccard index between the soil seed bank and the present plant community was large in the litter layer, but decreased with soil depth both in gaps and non-gap stands. The results show that soil seed banks are the main source of gap regeneration in the karst forests of Maolan and contribute significantly to gap regeneration.